The invention relates to a method of injecting a material into soil, the method comprising injecting a material which expands as a consequence of a chemical reaction into the soil through an injection bar.
The invention further relates to an apparatus for injecting a material into soil, the apparatus comprising an injection device for injecting a material which expands as a consequence of a chemical reaction, and an injection bar for feeding the material injected by the injection device into the soil.
Soil is improved and/or structures are lifted using a solution wherein a material which expands as a consequence of a chemical reaction is injected into the soil. An amount of the material to be injected may be determined by examining the properties of the soil in advance, e.g. by penetrometer measurement. The sufficiency of the injected material may then be checked afterwards by similar measurement for measuring the properties of the soil. However, such a process for determining the amount of the material to be injected is slow and unreliable. A solution is also known wherein a pressure sensor is arranged in the soil, and a signal obtained from the pressure sensor is interpreted to mean that the soil has become denser. On the basis of the signal obtained, an attempt is made to estimate when the soil has become dense enough. The solution is quite unreliable and, as mentioned above, it requires a separate sensor to be arranged in the soil. U.S. Pat. No. 6,634,831 discloses a solution wherein a reaction on the surface of the soil caused by injection is monitored. The solution thus involves monitoring a rise of the surface of the soil, and when such a reaction is detected, it is then determined that the soil has become sufficiently dense, and the injection is stopped. Such a solution is extremely useful and reliable, but its use requires good skills and, typically, the use of a laser measurement sensor or another reliable measurement sensor for detecting a reaction on the surface of the soil.